Originally Posted by suss6052
69 is way too high, try 35 mph in 6th gear for peak efficiency, although you really won't be getting anywhere in a hurry. 65 in 6th gear is right around 2400 rpm or so vs close to 2600 at 70 mph, ergo even going just 5 mph slower would be more efficient, but take a bit longer.
It actually drops .8 at 65 for some reason and and drops .5 at 70, don't ask me why. And by best mileage I mean on the freeway. You have a PM btw.